Born in Buenos Aires, Solano López began his career in 1953 working for the publishing house Columba where he illustrated the series "Perico y Guillerma". Working for Editorial Abril he met Héctor Germán Oesterheld, assigned to illustrate his series "Bull Rocket" for the magazine "Misterix". They collaborated on the series "Pablo Maran" and "Uma-Uma", before joining to start Oesterheld's publishing house Editorial Frontera. For the Frontera first publication of the monthly "Hora Cero", the team produced the series "Rolo el marciano adoptivo" and "El Héroe". López also alternated as artist on the "Ernie Pike" series with Hugo Pratt, Jorge Moliterni and José Antonio Muñoz. On September 4, 1957 in the publication of "Hora Cero Suplemento Semanal", the science-fiction series "El Eternauta" made its first appearance.

A success, "El Eternauta" came to the attention of the authorities as the series featured commentary of the political situation of Argentina and neighbouring Chile, prompting Solano López to flee for Spain to avoid possible arrest. In 1959 Solano López began working for Fleetway in Madrid and later London, producing artwork for a host of series, including "Galaxus: The Thing from Outer Space", "Pete's Pocket Army", "The Drowned World", "Janus Stark", and "Kelly's Eye".

Solano Lopez was dispatched to Europe in 1853 as minister plenipotentiary to Great Britain, France, and the Kingdom of Sardinia. Lopez went on to spend over a year and a half in Europe, most of it in Paris, where he attended military classes as a guest student in the École spéciale militaire de Saint-Cyr, drawing the attention of Napoleon III, who decorated him with the Order of the Legion of Honour for his military skills. He also served as a foreign military observer during the Crimean War. He purchased large quantities of arms and military supplies, together with several steamers, on behalf of the Paraguayan military. He also modernized the Paraguayan Army with the novelties he acquired in Europe, adopting the French Code and the Prussian System of military organization (receiving some praise for this innovation many years later). His diplomatic work also included organizing a project to build a new railroad and efforts to establish a French émigré colony in Paraguay. He installed the first electric telegraph in South America. Lopez also became a great admirer of the French Second Empire and developed a fascination with Napoleon Bonaparte. López later equipped his army with uniforms designed to match those of the Grande Armée and it was said that he also ordered for himself an exact replica of Napoleons crown., yet this remains unproven.

After taking office, López opted to continue most of the policies of economic protectionism and internal development adopted by his predecessors. However, he broke sharply with the traditional policy of strict isolationism in foreign affairs that was favored by previous Paraguayan leaders. López instead embarked on a more activist approach to international policy. He had, as his great ambition, to strategically position Paraguay enough to represent a credible “third force” in the ongoing political and military rivalry between Argentina and Brazil over the Rio de la Plata Basin. López wanted Paraguay to compete with the continent's major powers in the struggle for spoils and regional dominance. In pursuit of this goal López sought to organize the region’s smaller nations into a political coalition designed to off-set the power and influence of the Brazilians and the Argentines. López found an eager ally in President of Uruguay Bernardo Berro, another leader whose country was frequently menaced by the various intrigues of the continent's two great powers. Berro and López would quickly conclude an alliance and López would begin a massive expansion and reorganization of the Paraguayan military, introducing mandatory military service for all men along with other reforms. Under López, Paraguay grew to possess the best-trained and well-equipped military in the region.

Having returned to Argentina, Solano López resumed collaboration with Oesterheld on "El Eternauta II" in 1968 with a new publishing house, Editorial Records. He also started work on science-fiction saga "Slot-Barr" with writer Ricardo Barreiro, and the police series "Evaristo" with Carlos Sampayo. In the late 1970s Solano López again fled Argentina following persecution from the authorities, and from Madrid he arranged the publication of both "El Eternauta" and "Slot-Barr" with the Italian magazines "LancioStory" and "Skorpio".

In November 1859, López was on board the war steamer "Tacuari", which was attacked by British Royal Navy ships attempting to pressure his father into releasing a British citizen from prison. The British consul who ordered the attack was Sir William Dougal Christie, later replaced by Edward Thornton who personally supported Argentina in the War of the Triple Alliance.